Have you ever seen a train pass by a station but no one gets in or out? That's because it's a ghost station! A ghost station is a subway or train station that is no longer used or accessible to the public.
Just like old toys that are no longer played with, sometimes train stations are no longer needed. Sometimes people move away from an area, or different routes are built. Or, sometimes the city changes and the station becomes unsafe.
When a subway or train station becomes a ghost station, it's still there, but nobody uses it anymore. You might go past it on a train and see it, but you can't go there. Some stations get closed up and hidden behind walls, while others might be used for storage or turned into something new like a restaurant or storage area.
So next time you take a trip on a train or subway and you see a station with no people getting on or off, it might just be a ghost station!